Wicked; fiendish.
Derived from 'Mephistopheles,' meaning:
I. A devil in medieval legend and later literary and operatic works, to whom Faust, or Faustus, sells his soul for knowledge and power.
II. A crafty, powerful, sardonic person.
Early 19th century: Mephistopheles, an evil spirit to whom Faust, in the German legend, sold his soul.